[Devils Advocate]

If you think a spirit level will indicate when the aircrafts attitude changes, you need to reconsider. How does Bob Hoover do his famous barrel roll with a constant acceleration vector keeping his tea almost perfectly level? He even pours a cup of tea while rolling the aircraft.

This could be used to answer a common FE issue where the statement defines it "impossible that earth is spinning and hurtling through space at high speeds and yet we don't feel it". looks like that cup of tea isn't "experiencing" much feedback from its high speed manoeuvering either.......

[xenotolerance]

Another, albeit less dramatic example of why a level on a plane doesn't have anything to do with curvature:



I also strongly recommend reading the Metabunk thread on this topic, that StinkyOne already linked to: https://www.metabunk.org/explained-why-a-spirit-level-on-a-plane-does-not-show-curvature-corrections.t8741/

OP just ignored it, so it may have escaped attention, but it's really quite thorough.

[Luposian]

Oh... my... goodness!  I was gonna bring up the whole Chinese Spacelab article as a question, but the sheer lunacy of the FE mindset is simply unbearable.

Oh, fluffy poop... I'll do it anyways:

https://www-m.cnn.com/2018/04/01/asia/tiangong-1-china-space-lab-falls-intl/index.html

If the earth is flat, how does a satellite travel AROUND the earth?  What would cause it to crash back to earth?

Of course there are also those who say man has never been to the moon and that all NASA info/pictures are made up... but to them, I say, then was the Challenger explosion faked? Or maybe it was a government conspiracy, like JFK and 9/11?  If the earth is flat, why "go up"?  There is nothing "up there".  Just a bunch of fireflies stuck up in that bluish black thing "up there"!

I await some response and hope it doesn't make me laugh so hard I pass out from a lack of oxygen... :-D